Variable delivery pump



Feb. 7, 1950 J. F. HOFFER VARIABLE DELIVERY PUMP 3 Sheets-Sheet 1 Filed Feb. 20. 1946 INVENTOR.

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Feb. 1, 1950 F, HOPPER 2,496,915

VARIABLE DELIVERY PUMP Filed Feb. 20, 1946 s Sheets-Sheet 2 Feb. 7, 1950 J. F. HOFFER VARIABLE DELIVERY PUMP 3 Sheets-Sheet 5 Filed Feb. 20. 1946 Patented Feb. 7, 1950 VARIABLE DELIVERY PUMP James F. Hotter, Detroit, Mich., assignor to Superdraulic Corporation, Dearborn, Mich., a corporation of Michigan Application February 20, 1946, Serial No. 649,021

6 Claims.

The present invention relates to improvements in fluid displacement means such as pumps or motors, and particularly relates to improvements in high pressure plunger type, variable delivery pumps.

One of the primary objects of the present invention is to provide improvements in the manner of accurately varying the delivery-of a variable delivery pump.

Another object of the invention is to provide improvements in variable delivery pumps oi the type mentioned, which operate at high pressures, up to and in excess of 5,000# per square inch.

Another object of the invention is to incorporate the advantages and results of the pumps disclosed in the co-pending applications of James F. Hoffer, Serial No. 541,167, filed June 20, 1944 and Serial No. 615,793, filed September 12, 1M5 now Patents 2,431,175 and 2,431,176, respectively, granted Nov. 18, 1947, in the variable delivery pumps.

. Another object of the invention is to provide simplified constructions for varying the delivery of a variable delivery pump.

Other objects of the invention will become apparent from the following specification, the drawings relating thereto and from the claims hereinafter set forth.

In the drawings, in. which like numerals are used to designate like parts in the several views throughout:

Fig. 1 is a cross-sectional view of a variable delivery pump embodying features of the present invention, taken substantially along the line i--I of Fig. 2;

Fig. 2 is an axial, cross-sectional view, with parts in elevation, taken substantially along the line 2-4 of Fig. i;

Fig. 3 is a cross-sectional view, taken substantially along the line 3-4 of Fig. 2;

Fig. 4 is an end elevational view taken substantially along the line 4 i of Fig. 1;

Fig. 5 is an end elevational view taken substantially along the line 5-5 of Fig. 1;

Fig. 6 is a fragmentary, axial cross-sectional view of the inner end of the pintle;

Fig. 7 is a cross-sectional view, with parts in e1evation, taken substantially along the line 'l-l of Fig. 2;

Fig. 8 is a view generally similar to Fig. 1 and I illustrating diagrammatically the elliptical reaction rings or members in different positions; and, Fig. 9 is a view similar to Fig.8 and illustrating a modified form thereof.

In general, the pump of the present invention is a radial type, variable delivery plunger pump arranged so that centrifugal force maintains the plunger rollers in contact with elliptical reaction rings. The plungers are fitted to cylinders in a rotor in a plurality of banks of a number of plungers per bank, there being eleven plungers per bank in the embodiment illustrated. The rotor rotates on a fixed pintle having suitable ducts and ports for directing the oil from the inlet into those cylinders passing through two opposite quadrants, also for directing the oil delivery out of those cylinders passing through the other two opposite quadrants.

Each plunger makes two inlet and two delivery strokes per revolution. A sturdy equalizing axle journaling a roller at each end is universally attached to the outer end of each plunger and is preferably of the type disclosed and claimed in the co-pending application of James F. Hofler Serial No. 541,167, filed June 20, 1944. This construction provides ample bearing areas for the plunger load components exerted radially and rotatively on the axle bearing surfaces and insures substantially zero side loading of the plunger.

In the variable delivery pump here illustrated, two banks of eleven plungers each are arranged in a single rotor. The plungers in the two banks are arranged in parallel relation. Each pair of parallel cylinders is in open communication by means of a drilled passage in the rotor.

The plunger rollers at each bank roll against a separate elliptical reaction ring. These reaction rings are rotatably mounted in the pump housing and are geared together so that they rotate in opposite directions in response to rotation of the volume control gear.

At full delivery, the major axes of the elliptical reaction rings are parallel and at zero delivery, the major axes are apart. Under the latter condition, the net delivery stroke is zero since the displacement of these plungers moving radially outwardly exactly equals the displacement of these plungers moving radially inwardly in both delivery quadrants and both suction quadrants.

As the angle between the major axes is reduced from 90, the net plunger displacement increases. When this angle becomes 0, the major axes are parallel and both plungers of a pair of parallel plungers reciprocate in phase through full delivery and suction strokes.

Provision for a simple spring type plunger return means is preferably incorporated and is preferably of the construction disclosed and claimed in the co=pending application of James 3 F. Hoffer, Serial No. 615,793, filed September 12, 1945. This is insurance against failure of plungers to return when pumps are operated below the speed at which centrifugal force is adequate, for example at speeds below approximately 100 R. P. M.

The variable delivery pumps are equipped with one of a number of different type volume controls which are interchangeably mounted on the pump. A sensitive manual dial type control such as that shown may be mounted on either side of the pump.

Plunger reaction loads exerted on the elliptical reaction rings are balanced through the volume control gear, the torque of one reaction ring balancing that of the other. Thus light and sensitive manual or automatic pressure and volume controls can be interchangeably employed.

A small oil circulating pump is preferably incorporated for the purpose of circulating oil under near zero pressure direct from the oil tank through the pump housing and back to the tank. This insures sufilciently low pump housing temperatures of the variable delivery pump under the condition of extreme pressure operation at zero or near zero delivery.

Referring to the drawings, a pump embodying features of the present invention. is illustrated and such pump includes a housing having a central section 1. The section I is open at its ends and is adapted to have end housing members 2 and 3 secured thereto by suitable screws, or the like, which serve to enclose the housing. The central section I has a circular inner surface indicated at I and has a pair of diametrically opposed openings and 8 formed therein.

A pair of separate reaction members I and 8 are disposed within the housing. The reaction members 1 and 8 have the same fixed contours. with the peripheries thereof circular, as indicated at 8, and the inner reaction surfaces thereof e1- liptical in shape, as indicated at Ill. The members I and 8 are mounted for rotation within the housing and are each formed with an annular shoulder l l which forms ball bearing races against which ball bearings I2 hear. The ball bearings l2 are also engaged within the corners formed by the adjacent portions of the inner surface 4 of member I and the end member 2, and the corner formed by the annular shoulder l3. The reaction members 1 and 8 are spaced slightly from each other and the facing surfaces thereof are formed with annular grooves II and I5 within which ball bearings it are received. Thus, the reaction members 1 and 8 may be rotated with respect to the housing and also with respect to each other.

In order to rotate the reaction members i and 8, annular portions are removed from the adjacent peripheries of members 1 and 8 and ring Sears l5 and I1 are formed or fixed thereon.

The volume delivered by the pump is controlled by relatively rotating the reaction members I and 8. as will be better understood from the later description, and, in order to rotate the members I and 8, a manual volume control mechanism is mounted within one of the openings 5 or 8. Such manual control includes a control gear which is positioned through opening 5, in the embodiment illustrated, to mesh with gears It and H. The gear has a shaft portion 2| integral therewith which projects through the opening 5 and which has a hand knob 22 fixed thereto for rotation therewith. The shaft 2| is received within a sleeve member 23 with needle bearings 24 interposed between the adjacent surfaces of the inner end thereof.

In order to control the movement or adjustment between zero delivery and full deliver a groove 25 is formed in the body of the gear shaft and extends only part way around the periphery thereof. A ball 25 is received within an opening 21 in the sleeve 23, as best shown in Fig. 3, and when the parts are assembled the ball projects within the groove 25. The ball 26, in abutting against the ends of the groove 25, serves to limit the rotative movement thereof.

When it is desired to get greater relative movement between the reaction members, the groove 25 is made longer, as indicated at 25' in Fig. 9, and the opening 21 is made longer, as indicated at 21'. In the modification shown in Fig. 9, sufficient rotative movement is allowed so that flow through the pump may be reversed.

The volume control assembly is mounted in the pump housing by means of screws 28 which are passed through the housin through openings in an annular flange formed on the sleeve 23.

An opening or window 29 is formed through the hand knob 22 and a pointer 30 is fixed to the knob for rotation therewith. Suitable indicia 3| (Fig. 4) are shown on the outer face of the sleeve flange 23 so that the operator can see the relative positions of the reaction rings.

A set screw 32 jis-receive'd through the member 22 and is adapted to engage the peripheral edge of the sleeve flange in order to locate the reaction members in the position desired.

A ball bearing assembly 33, having inner and outer races with balls interposed therebetween, is positioned between the shaft 2| and the'inner surfaces of sleeve 23. The gear 28 may thus be easily turned by turning the knob 22, and the reaction members 1 and 8 are correspondingly rotated in opposite directions due to the intermeshing relationship between gear 20 andgears l8 and H.

A pinion 35 is mounted within a sleeve 38 within the opposite opening 6 in intermeshing relationship with gears l6 and H. The outer end of the shaft on gear 35 may have a pointer 31 mounted thereon which points to suitable indicia formed on the outer face of annular flange 38, which is formed integral with sleeve 35. The operator may thereby view the setting from either side of the pump. The gear 35 together with sleeve 36 are mounted to the housing by means of suitable screws 39 which are received into the housing through openings in the flange 38.

The housing 2 serves to provide the inlet and outlet ports for the pump and also serves as the mounting for a stationary or fixed pintle 40 which is fixedly mounted within an axial opening ll formed in housing 2.

The pintle 40 is formed with longitudinally extending passageways 42, 43, 44 and 45 therealong which terminate adjacent one end to close that end of the passage and which are plugged by means of individual plugs at the other end of the passageway, as in the Hoffer application Serial No. 541,176,.above mentioned.

Inlet and outlet ports are formed through the walls of the pintle communicating with their respective passageway. Inlet ports 46 and 41 communicate with inlet passageways l2 and 45, respectively; and outlet ports 48 and I9 communicate with outlet or pressure passageways 43 and 44, respectively. Ports 86 and I! are offset along and around the axis of the pintle with respect to each other; and ports 48 and 49 are offset along of a coupling 54.

and around the axis of the pintle with respect to each other. Ports 49 and 41 are aligned with respect to the longitudinal axis of the pintle and with respect to each other.

The member 2 has an axial bore 4| within which one end of the pintle 40 is received; and has a transverse bore forming an inlet passageway 50 and an outlet passageway 5| (Fig. 7). The inlet passageway 50 communicates directly with intake port 47 and communicates through an angled, cored passageway '52 with intake port 46. Pressure port 49 communicates directly with outlet passageway 5i, and the passageway 5| communicates with pressure port 48 through an angled, cored passageway 53.

An inlet conduit leads from a supply tank to the inlet 50 and is connected thereto by means An outlet or pressure conduit communicates with outlet 5| and is connected to the housing 2 by means of a coupling similar to 54. The outlet or pressure conduit then leads to the work mechanism (not shown).

The opposite end of the pintle 46 has a pair of ports 55 communicating with inlet passageway 45 which are longitudinally spaced with respect to each other, and has another pair of diametrically opposed, longitudinally spaced ports 56 which communicate with passageway 42. The pintle fill also has a pair of longitudinally spaced pressure ports 57 which communicate with passage 43 and has another pair of diametrically opposed pressure ports 58 which communicate with passageway at. one of each of the pairs of ports 55, 56, 51 and 58 lies in the same transverse position and the other of each of the pairs lies in another, same transverse position, there being one of thepairs for one of the banks of plungers and the other of the pairs for another bank. This will be more apparent from the description to follow.

Each of the pressure ports is preferably formed with a central groove or slot on the leading edge, each groove being of gradually increasing depth therearound, as described in Hofier application Serial No. 541,167.

The inlet passageways 82 and 45 are joined by common conduits 60; and outlet passageways 33 and 44 are joined by a common conduit 5!; both being located near the ports 55, 56, 5? and 58.

The pintle 45 projects inwardly of the housing i axially thereof and serves to rotatably support a pump rotor 62. The rotor 62 is driven by a drive shaft member 63 which is connected thereto by means of a universal coupling including member 64 which is pinned to the shaft 63 by pins 65 and a lock nut 56. The connection is the same as that disclosed in detail in the co-pending application Serial No. 615,793 and reference may be had thereto. As there disclosed, the face of member 64 is formed with diametrically spaced projections thereon which are slidably received in diametrically opposed slots formed in a coupling ring. The rotor 62 has diametrically opposed projections formed thereon which are slidably received in diametrically opposed slots in the ring. The projections on the rotor are spaced ninety degrees from the projections on the coupling member 64.

The drive shaft 63 extends through a central axial opening in the housing member 3 and is rotatably supported therein by means of axially spaced ball bearing assemblies 61 and 68. The shaft projects outwardly beyond the housing member 3 and is connected to a suitable drive means. An oil seal 69 is disposed within the opening of an end cap 10, which is secured to the housing member 3, and bears against the drive shaft in the usual way.

A conventional vane type, low pressure pump indicated at II is disposed within the housing member 3 between ball bearing assemblies 61 and 68. An inlet port 12 is provided in the housing member 3 and is adapted to be connected to a conduit leading to the oil tank or reservoir. The opening 12 communicates through an opening 13 to the low pressure side of the vane pump and the coolant is drawn into the pump through the inlet 13 and discharged from the pressure side of the pump, indicated at H. The coolant then circulates through the housing I and is discharged through an opening or openings 15 in housing member 2. A conduit is connected to openings 15 and leads back to the tank. This circulating pump is preferably incorporated for the purpose of circulating oil or other coolant, under near zero pressure direct from the oil tank or reservoir through the pump housing and back to thetank. This insures sufliciently low pump housing temperatures of the variable delivery pump under the condition of extreme pressure operation at zero, or near zero, delivery.

The rotor 62 is formed with a plurality of banks of radially disposed bores 16 and-78, the bores 76 of one bank being uniformly disposed about the rotor and the bores 18 of the other bank also being uniformly disposed about the rotor and being axially aligned and parallel to each other. The bores 16 overlie and communicate with one of the pairs of ports 55, 56, 51 and 58; and the bores 18 overlie and communicate with the other of the pairs of ports. It will, therefore, be understood that separate intake and pressure ports, communicating with the lnlet and outlet passageways in the pintle, are pro-.

vided for each of the banks.

However, a detailed description of the construction and arrangement of the plungers and means interconnecting the plungers with the reaction members i and 8 of one of the banks or of one of the plungers will be suflicient for an understanding of the construction and arrangement of the other plungers and their interconnecting means. The plungers and interconnecting means are the same as those disclosed in detail in Hoffer applications serial No. 541,167 and Serial No. 615,793 and reference may be had thereto for a detailed description. The rotor 52 has a central opening 80 therethrough which rotates on the pintle 86 with one end of the rotor running against the adjacent face of housing member 2 and the other end connected to the drive 63. The rotor 62 is formed with axially spaced, annular grooves 84 which form therebetween outwardly directed annular flanges 86 and 88, the flanges 86 having the bores it for one of the banks of bores formed therethrough and the flange 88 having the bores '18 for the other bank of bores formed therethrough. The bores 16 extend completely through the rotor 62 from the outer end thereof through opening 80 and are of uniform diameter throughout their length. In the flange portions of the rotor, such as flange 86, transverse slots are cut through the bores 16 in the flange portion, in a direction transverse to the direction of rotation of the rotor, providing parallel faces 92 on opposite sides of eachbore. The purpose of the slot and the parallel faces 92 will be more apparent from the latter description.

A cylindrical plunger 94 is disposed within 7 each of the bores I6 (and also each of the bores 10). Such plungers 94 are adapted to reciprocate within their bores as the rotor 02 rotates and are moved outwardly by centrifugal force caused by such rotation and also by the action of the spring structure to be hereinafter described. The axial movement or position of the plungers is controlled through a connection between the outer ends of the plungers and the reaction members I and 8 as the rotor 62 rotates.

Each plunger 94 is formed with an annular, pressure-balancing recess 96 and is flat at its inner end. At the outer end it is formed with an integral projection 98 which is generally circular in cross section and which extends completely across the top of the plunger.

Means are provided for interconnecting each plunger 94 with the respective reaction members 1 and 0. which is of such a character that there is practically no side loading of the plunger and also of such a character that it is self-aligning at all times whereby the plunger load is equally divided on roller means which engage the reaction members.

Thus, interconnecting means include an axle or equalizing member generally indicated at I00. Such axle I is ruggedly constructed and includes a central portion having fiat parallel sides and having the outer end crowned. The outer sides of member I00 are formed to provide bearing trunnions I04 with the inner surfaces thereof flattened for proper lubrication. The central portion I02 is formed with a transversely extending recess I08 which is complementary in transverse section to the transverse sectional shape of projection 98 and is adapted to slidably receive the projection 90 therein. The recess I08 is formed in the direction of rotation of the rotor, and when positioned in the rotor the projection 90 extends in the same direction. The flat sides of central portion I02 are adapted to bear against the parallel sides 92 of slot 90 in the rotor as the plunger reciprocates.

Rollers or wheels II2 are rotatably mounted on the trunnion portions I04 of the axle I00, through bearing sleeves when assembled. The trunnions and wheels are received within the annular groove 84 with the peripheral portions of the wheels received within annular grooves II6 formed in the bases of groove I6.

Means are provided for lubricating the wheels through the plungers, as in Hoffer application Serial No. 541,167.

In assembly, the axle I00 is slidably mounted to the projection 98 on the plunger 94. This slidable connection will permit a slight aligning movement between axle I00 and plunger 94 in the direction of rotation of the rotor. The connection between groove I08 and projection 98 will permit a slight rocking action of the axle so that the wheels II2 are self-aligning in their engagement with the reaction members I and 8 as the rotor rotates.

Due to the self-alignment of the axle member I00 in its interconnection between the plunger 94 and the reaction members I and 8, there is practically no side loading on the plunger during rotation of rotor 62. The axle I00 is free, in a limited way, to slide and rock, in planes at right angles to each other, with respect to the plunger 94 and also with respect to the engaging surfaces 02. As the plunger is caused to reciprocate within its cylinder I6, the forces applied to the plunger are directly along its axis. Since the bore II is of uniform diameter throughout its length,

8, the piston 94 is completely supported throughout its stroke; that is, the outer portion of bore I6 engages the piston 94 when the piston is at the outer end of its stroke and such piston is supported completely along its length throughout its stroke.

Spring means are preferably employed which are connected to each of the axles I00, and through such axles connected to pistons 94, to urge the pistons outwardly. Such means includes the provision of bores I in the rotor 62, there being one of such bores I20 for each of the bores I6 and parallel thereto. A coil spring I22 is disposed in each of the bores I20 with the inner end of the spring abutting against the bottom of the bore and with the outer end received within a tubular member I24. Each tubular member is slidably received within its bore I20 and is urged to its outer position by its spring I22. The tube is guided by the side walls of its bore I20 so that its movement is along the axis of the bore.

The bores I20 as mentioned above, are parallel to their respective bores I6, and the center lines of bores I20 are disposed in the same plane of rotation as the center lines of bores I6. A rigid pin I25 interconnects the outer end of each sleeve I24, with its adjacent axle I00. The pin is located at the transverse center of the axle I00 and is received within a pivot opening therein. The outer end of each spring may be confined by abutment against that portion of the pin I25 which extends across the sleeve I24. An annular groove I28 is formed around the rotor 62 in the plane of the axes of bores I6 and I20 to permit the in and out movement of the pin I26.

The action of the spring structure is the same as in Holler application Serial No. 615,793, referred to.

The adjacent parallel pairs of bores I6 and I8 are annularly enlarged slightly adjacent the inner ends thereof as indicated at I30 and each of such pairs of bores are in open communication with each other through a passageway I 32 therebetween. Passageways I32 are formed in the central portion of rotor 62. Thus, each adjacent parallel pairs of bores I8 and I8 are in communication with each other under, or inwardly of, the pistons 94.

In the operation of the machine of the present invention, with the driving member 63 driven to rotate the rotor 62 in a counter clockwise direction (Fig. 1) for example; outward movement of the plungers is effected by centrifugal force, or with the assistance of springs I22 at low speeds. Inward movement of the plungers is effected by the action of the reaction members I and 8 on their respective banks of plungers. Oil, or other fluid, is drawn into the inlet 50 from the source such as a tank or reservoir, and enters inlet passageways 42 and 45 in the pintle 40. Passageways 42 and 45 are in open communication through passageway 60. The oil passes from passageways 42 and 45 through pintle ports and 55, respectively.

Assuming that the volume control member 22 is set for maximum delivery, the major axis of the elliptical reaction members are aligned and parallel. The reaction members are then in the position shown in Fig. 1. The plungers of each pair of adjacent, parallel plungers then move outwardly and inwardly in phase with each other. As they pass across the suction quadrants oil is drawn into their bores I6 and 10 through ports 50 and 06. Upon continued rotation of the rotor the pistons are moved to the pressure quadrants and are moved inwardly by the reaction rings 1 and 8 and the connection between the plungers and the reaction rings which builds up the pressure and effects the discharge of the fluid under pressure through ports 51 and 58 into pressure passageways 43 and 44. Passageways 43 and 44 are in open communication through passageway iii. The fluid under pressure is then discharged through opening 5! and passes therefrom through a suitable conduit to a working means (not shown).

By turning the control member 22 so that the reaction rings I and 8 are rotated relative to each other to the position shown in Fig. 8, where the major axis of the reaction members are 90 apart, the pump delivery is reduced to zero. The plungers of each adjacent pair are thereby placed out of phase with each other so that one of the plungers is in the extreme of its outward movement when the other plunger is in the extreme of its inward movement. The fluid that is drawn into the cylinder of one of the plungers on its outward movement comes from the cylinder of the other plunger during its inward movement through the interconnecting passageway I32 during the few degrees of rotation when the plungers arepassing over the lands between the pintle ports. During the time that the plungers are passing over the pintle ports the fluid passes main= ly through the larger pintle ports and intercommunicating pintle passageway and partly through the smaller passageway I32. One of the plungers is thus moving outwardly while the other one is moving inwardly with the fluid in the cylinders passing back and forth through passageway I32.

The two. extreme positions of the reaction members have been described above, that is, the position for maximum delivery and the position for zero delivery. It will be readily appreciated that any volume between zero and maximum may be easily attained by properly adjusting the control member 22 which results in varying the phase relationship between the plungers of each pair. At the intermediate positions a portion of the fluid in the adjacent cylinders which pass back and forth through passageway i32. At maximum delivery, there is no interchange of fluid between the cylinders through passageway i32.

Formal changes may be made in the specific embod ments of the invention described without departing from the spirit and substance of the invention the scope of which is commensurate with the appended laims. i

What is claimed is:

1. In a fluid power device, a housing, a pair oi substantially elliptical reaction members disposed within said housing, means mounting said reaction members for relative rotation with respect to each other, rotor means having a pair of axially spaced, radial bores therein disposed within said housing, a plunger in each bore, means interconnecting the outer end of each plunger with its reaction member to effect radial movement there= of upon rotation of said rotor, fluid conduit means communicating with said bores, other fluid cond-uit means formed in said rotor interconnecting said bores. and means to rotate said reaction members so that the major axes thereof may be displaced with respect to each other between zero and ninety degrees.

2. In a fluid power device, a housing, a pair of non-circular reaction members of fixed contour disposed within said housing, means mounting said reaction members for relative rotation with respect to each other, a rotor having a pair of axially spaced, radial bores therein disposed within said housing, a plunger in each bore, means interconnecting the outer end of each plunger with its reaction member to effect radial movement thereof upon rotation of said rotor, fluid conduit means communicating with said bores, other fluid conduit means formed in said rotor interconnecting said bores, and means to rotate said reaction members so that the major axes thereof may be displaced with respect to each other between zero and ninety degrees.

3. In a fluid power device, a housing, a pair of non-circular reaction members of fixed contour disposed within said housing, means mounting said reaction members for relative rotation with respect to each other, a rotor having a pair oi. axially spaced, radial bores therein disposed within said housing, a plunger in each bore, means interconnecting the outer end of each plunger with its reaction member to eifect radial movement thereof upon rotation of said rotor, fluid conduit means communicating with said bores, other fluid conduit means formed in said rotor interconnecting said bores, means movable to rotate said reaction members so that the major axes thereof may be. displaced with respect to each other, and means interconnecting said movable means with said reaction members, said last named means being so constructed and arranged that a force tending to move said movable means is not exerted on said movable means by said reaction members and does not efiect movement of said movable means.

4. In a fluid power device, a housing, a pair of substantially elliptical reaction members of fixed contour disposed within said housing, means mounting said reaction members for relative rotation with respect to each other, a rotor having a pair of axially spaced, radial bores therein disposed within said housing, a plunger in each bore, means interconnecting the outer end of each plunger with its reaction member to effect radial movement thereof upon rotation of said rotor, fluid conduit means communicating with said bores, other fluid conduit means formed in said rotor intercommunicating said bores, and means to rotate said reaction members so that the major axes thereof may be displaced with respect to each other.

5. In a fluid power device, a housing, a pair of substantially elliptical reaction members of fixed contour disposed within said housing, means mounting said reaction members for relative rotation with'respect to each other, a rotor having a pair of axially spaced radial bores therein disposed with said housing, a plunger in each bore, means interconnecting the outer end of each plunger with its reaction member to efieot radial movement thereof upon rotation of said rotor, fluid conduit means communicating with said bores, other fluid conduit means formed in said rotor interconnecting said bores, and means to rotate said reaction members in opposite directions so that the major axes thereof may be displaced with respect to each other.

6. In a fluid power device, a housing, a pair of substantially elliptical reaction members of fixed contour disposed within said housing, means mounting said reaction members for relative rotation with respect to each other, a rotor having a pair of axially spaced, radial bores therein disposed within said housing, a plunger in each bore, means interconnecting the outer end of each plunger with its reaction member to effect radial movement thereof upon rotation of said rotor,

inlet and outlet fluid conduit means communicating with said bores, other conduit means formed in said rotor intercommunicating said bows; and means to rotate said reaction members so that the major axes thereof may be displaced with 5 respect to each other between zero and ninety degrees, said last named means and said reaction members being so constructed and arranged that at full delivery said major axes are substantially parallel and at zero delivery said major axes are 10 substantially ninety degrees apart.

JAMES F. HOFFER.

REFERENCES CITED The following references are of record in the 15 file of this patent:

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